Weak due to a bad meal? (4)
I believe the answer is:
lame
'weak' is the definition.
(similar in meaning)
'a bad meal?' is the wordplay.
'a bad' indicates an anagram.
'meal' is an anagram of 'LAME'.
'due to' acts as a link.
(Other definitions for lame that I've seen before include "Hobbling" , "Imperfect - material" , "Disabled in leg or foot" , "Unable to walk without difficulty" , "Walking with a limp" .)