King in tangled bush, forsythia maybe (5)
I believe the answer is:
shrub
'forsythia maybe' is the definition.
(I know that forsythia is a type of shrub)
'king in tangled bush' is the wordplay.
'king' becomes 'R' (abbreviation for rex, king in Latin).
'in' is an insertion indicator.
'tangled' indicates anagramming the letters.
'bush' anagrammed gives 'shub'.
'r' going within 'shub' is 'SHRUB'.
(Other definitions for shrub that I've seen before include "Woody plant smaller than a tree" , "Plant - brush (anag)" , "box, say" , "Myrtle or Rosemary, say" , "Perhaps Heather" .)