In the navy, he adds a good deal to a reshuffled team (7)
I believe the answer is:
matelot
'in the navy he adds a good' is the definition.
The definition suggests a singular noun which matches the answer.
'deal to a reshuffled team' is the wordplay.
'deal' becomes 'lot' (synonyms).
'to a' is a charade indicator (letters next to each other) (I've seen this in other clues).
'reshuffled' indicates an anagram.
'team' with letters rearranged gives 'mate'.
'lot' put after 'mate' is 'MATELOT'.
Can you help me to learn more?
(Other definitions for matelot that I've seen before include "One at sea" , "Rating" , "A lot met (anag) - sailor" , "Sailor (slang from French)" , "One sailor" .)