News boss about to join army shows merit (7)
I believe the answer is:
deserve
'merit' is the definition.
(I know that merit can be written as deserve)
'news boss about to join army' is the wordplay.
'news boss' becomes 'ed' (short for editor).
'about' is a reversal indicator.
'to join army' becomes 'serve' (as in serving in the army).
'ed' back-to-front is 'de'.
'de'+'serve'='DESERVE'
'shows' is the link.
(Other definitions for deserve that I've seen before include "Be entitled to" , "Merit (something)" , "Justify" , "rate" , "Severed (anag)" .)