Say no more and concede it's superficial (7)
I believe the answer is:
shallow
'superficial' is the definition.
(similar in meaning)
'say no more and concede' is the wordplay.
'say no more' becomes 'sh' ('sh' means stop talking).
'and' means one lot of letters go next to another.
'concede' becomes 'allow' (synonyms).
'sh'+'allow'='SHALLOW'
'it's' acts as a link.
(Other definitions for shallow that I've seen before include "Insincere" , "Lacking depth" , "Without depth" , "justice" , "Of no great depth" .)