Bring in different set, getting serious (7)
I believe the answer is:
earnest
'serious' is the definition.
(similar in meaning)
'bring in different set getting' is the wordplay.
'bring in' becomes 'earn' (synonyms).
'different' indicates anagramming the letters.
'getting' says to put letters next to each other.
'set' anagrammed gives 'est'.
'earn'+'est'='EARNEST'
(Other definitions for earnest that I've seen before include "Serious; down-payment" , "Determined - heartfelt" , "Firm" , "Oscar Wilde wrote ''The importance of Being . . . . . . . '' (7)" , "Sincere -- humourless" .)