Complaining right away of being sick (6)
I believe the answer is:
ailing
'sick' is the definition.
(similar in meaning)
'complaining right away' is the wordplay.
'complaining' becomes 'railing' (railing is a kind of complaining).
'right' becomes 'r' (common abbreviation).
'away' indicates named letters should be taken away.
'railing' with 'r' taken away is 'AILING'.
'of being' acts as a link.
(Other definitions for ailing that I've seen before include "Sickly, poorly" , "Ill" , "feeling sick" , "Infertile" , "not doing very well" .)