Key (4)

'key' is the definition.
(I have seen 'Musical key' mean 'clef' so perhaps 'key' could also mean 'clef')
This is the entire clue.
(Other definitions for clef that I've seen before include "Sign at start of stave" , "Staff note" , "Symbol written on sheet music to indicate pitch" , "Musical pitch indicator" , "Sign of (musical) pitch" .)
'key' is the definition.
(key can mean a small island)
This is all the clue.
(Other definitions for isle that I've seen before include "Dogs, maybe" , "Such as Man or Bute" , "Small landmass" , "Could be Man" , "See 10 Down" .)
(Other definitions for hash that I've seen before include "Recooked dish for shah" , "Stew - key" , "What signifies a number" , "Jumble or mixture for shah" , "Complete mess" .)
'key' is the definition.
(both can mean a small island)
This is all the clue.
(Other definitions for islet that I've seen before include "Stile (anag)" , "Eyot, key" , "Little bit of land" , "Very small area surrounded by water" , "Ait or key" .)
'key' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for crucial that I've seen before include "Of paramount importance" , "Of critical importance, decisive" , "Of great importance" , "Of essential importance" , "Vitally important" .)
(Other definitions for fob that I've seen before include "Small watch pocket" , "Chain for a pocket watch" , "Kind of watch carried in pocket" , "Ornament worn on watch chain" , "It is worn hanging from a watch-chain" .)