Thin swans almost cry out (7)
I believe the answer is:
scrawny
'thin' is the definition.
(similar in meaning)
'swans almost cry out' is the wordplay.
'almost' means to remove the first letter.
'out' is an anagram indicator (out can mean wrong or inaccurate).
'swans' with its initial letter taken off is 'wans'.
'wans'+'cry'='wanscry'
'wanscry' is an anagram of 'SCRAWNY'.
(Other definitions for scrawny that I've seen before include "Thin -- underfed" , "Being underweight" , "Thin and bony" , "Meagre" , "Unhealthily thin" .)