Long form of chit (4)

I believe the answer is:

itch

'long' is the definition.
(to long or itch for something is to desire it)

'form of chit' is the wordplay.
'form of' is an anagram indicator (the letters need to be in another 'form').
'chit' anagrammed gives 'ITCH'.

(Other definitions for itch that I've seen before include "Contagious skin infection" , "source of irritation" , "Desire; irritation" , "Teasing desire" , "Longing; anag. of 19" .)

I've seen this clue in the Evening Standard.

Want a hint initially instead of a full solution? Install my app