Complaint caught by the aged? (4)
I believe the answer is:
cold
'complaint' is the definition.
(cold is a kind of disease)
'caught by the aged?' is the wordplay.
'caught' becomes 'c' (cricket abbreviation).
'by' says to put letters next to each other.
'the aged?' becomes 'old' (I've seen this before).
'c'+'old'='COLD'
(Other definitions for cold that I've seen before include "Dead" , "Lacking emotion" , "Chilly; unemotional" , "Unemotional; wintry" , "See 12" .)