Don’t strike boy in hat (7)
I believe the answer is:
stetson
'hat' is the definition.
(Stetson is an example)
'don't strike boy' is the wordplay.
'don't strike' becomes 'stet' (printing term meaning leave alone or don't strike).
'boy' becomes 'son' (synonyms).
'stet'+'son'='STETSON'
'in' is the link.
(Other definitions for stetson that I've seen before include "St Neots (anag.)" , "Hat with broad brim and high crown" , "Ten-gallon hat" , "No tests (anag.)" , "Style of hat" .)