I will get head cold, say (7)
I believe the answer is:
illness
'cold say' is the definition.
(cold is a kind of illness)
'i will get head' is the wordplay.
'i will' becomes 'I'll' (abbreviation).
'get' is a charade indicator (letters next to each other).
'head' becomes 'ness' (type of geographical point).
'ill'+'ness'='ILLNESS'
(Other definitions for illness that I've seen before include "Sick condition" , "Upset" , "Indisposition, sickness" , "Disease, sickness" , "Malady, sickness" .)