A bit depressed, having inflammation (7)
I believe the answer is:
whitlow
'inflammation' is the definition.
(I have seen 'Inflammation of finger ' mean 'whitlow' so perhaps 'inflammation' could also mean 'whitlow')
'a bit depressed' is the wordplay.
'a bit' becomes 'whit'.
'depressed' becomes 'low' ('low' can be a synonym of 'depressed').
'whit'+'low'='WHITLOW'
'having' is the link.
(Other definitions for whitlow that I've seen before include "Small abscess under a nail" , "Inflammation of finger(tip)" , "gathering" , "Painful inflammation beside nail" , "Growth" .)