She didn't want her boyfriend to have long hair! (7)
I believe the answer is:
delilah
'she' is the definition.
'didn't want her boyfriend to have long hair' is the wordplay.
I cannot quite see how this works, but
'her' could be 'delila' and 'delila' is found within the answer.
A single letter 'h' remains which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for delilah that I've seen before include "Dangerous temptress - Samson's girlfriend" , "She betrayed Samon to the Philistines" , "Seductive woman" , "Samson's false girl-friend" , "She cut Samson's hair" .)