Appropriate for everyone to visit seaside town in retirement (7)
I believe the answer is:
trouser
'appropriate' is the definition.
(I've seen this before)
'for everyone to visit seaside town in retirement' is the wordplay.
'for everyone' becomes 'U' (Universal film certificate).
'to visit' indicates putting letters inside (inserted letters visit others).
'seaside town' becomes 'resort' (seaside resort).
'in retirement' says the letters should be written backwards (retire can mean to go back or backwards).
'u' placed into 'resort' is 'resuort'.
'resuort' reversed gives 'TROUSER'.
(Other definitions for trouser that I've seen before include "Pocket (slang)" , "Our rest (anag)" , "For oneself" , "Pocket (something)" , "Appropriate" .)