Caught old man getting fat (6)
I believe the answer is:
chubby
'fat' is the definition.
(similar in meaning)
'caught old man' is the wordplay.
'caught' becomes 'c' (cricket abbreviation).
'old man' becomes 'hubby' (I've seen this in another clue).
'c'+'hubby'='CHUBBY'
'getting' is the link.
(Other definitions for chubby that I've seen before include "Fat in the face" , "Roundly plump" , "Overweight" , "On the plump side" , "Plumb and round" .)