British tree production has a cap (5)
I believe the answer is:
beret
'a cap' is the definition.
(I know that beret is a type of cap)
'british tree production' is the wordplay.
'british' becomes 'b' (abbreviation e.g. in BBC).
'production' indicates an anagram.
'tree' with letters rearranged gives 'eret'.
'b'+'eret'='BERET'
'has' acts as a link.
(Other definitions for beret that I've seen before include "Brimless French headgear" , "Round flattish cap" , "Soft round cap without a peak" , "French style cap" , "Soft flat hat" .)