The cold leg, perhaps, I had (5)
I believe the answer is:
gelid
'the cold' is the definition.
(I've seen this in another clue)
'leg perhaps i had' is the wordplay.
'perhaps' indicates anagramming the letters.
'i had' becomes 'I'd' (contraction).
'leg' is an anagram of 'gel'.
'gel'+'id'='GELID'
(Other definitions for gelid that I've seen before include "Glacial" , "Extremely cold, frozen" , "Icy cold - glide (anag)" .)