Girl with hat is a leech, for example (7)
I believe the answer is:
annelid
'a leech for example' is the definition.
(leech is a kind of annelid)
'girl with hat' is the wordplay.
'girl' becomes 'anne' (I've seen this before**).
'with' means one lot of letters go next to another.
'hat' becomes 'lid' ('lid' can be a synonym of 'hat').
'anne'+'lid'='ANNELID'
'is' acts as a link.
(Other definitions for annelid that I've seen before include "leech, for example" , "leech, perhaps" , "Lindane (anag.); a kind of worm" , "Earthworm or leech" , "Class of worms" .)