Merit of newspaperman about to join army (7)
I believe the answer is:
deserve
'merit' is the definition.
(synonyms)
'newspaperman about to join army' is the wordplay.
'newspaperman' becomes 'ed'.
'about' says the letters should be written backwards.
'to join army' becomes 'serve' (as in serving in the army).
'ed' reversed gives 'de'.
'de'+'serve'='DESERVE'
'of' is the link.
(Other definitions for deserve that I've seen before include "Warrant" , "rate" , "Justify" , "Merit (something)" , "Severed (anag)" .)