Some fear a chesty cause of discomfort (7)
I believe the answer is:
earache
'discomfort' is the definition.
(I have seen 'Aural discomfort ' mean 'earache' so perhaps 'discomfort' could also mean 'earache')
'some fear a chesty cause' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'EARACHE' is hidden in the letters of 'fear a chesty cause'.
'of' is the link.
(Other definitions for earache that I've seen before include "Aural discomfort" , "may involve hammer and anvil" , "Otic pain" , "stabbing in vestibule?" , "Lughole pain" .)