Star with lowered head? A cape's in need of a trim (7)
I believe the answer is:
unshorn
'in need of a trim' is the definition.
'star with lowered head? a cape's' is the wordplay.
'star with lowered head?' becomes 'uns' (I can't explain this - if you can you should give a lot more credence to this answer).
'a cape' becomes 'horn' (I've seen this before).
'uns'+'horn'='UNSHORN'
(Other definitions for unshorn that I've seen before include "still having woollen coat on" , "Of hair or wool, not cut" .)