Girl with head of hair like a leprechaun? (5)
I believe the answer is:
irish
'like a leprechaun?' is the definition.
(I've seen this in another clue)
'girl with head of hair' is the wordplay.
'girl' becomes 'iris' (girl's name).
'with head of' suggests taking the first letters.
The first letter of 'hair' is 'h'.
'iris'+'h'='IRISH'
(Other definitions for irish that I've seen before include "Gaelic language" , "Native to Erin" , "like Wexford" , "of Hibernia" , "Like Wilde or Yeats" .)