Newly promoted male avoided underwater missile (7)
I believe the answer is:
torpedo
'underwater missile' is the definition.
(I've seen this before)
'newly promoted male avoided' is the wordplay.
'newly' indicates an anagram.
'male' becomes 'm' (common abbreviation).
'avoided' is a deletion indicator.
'promoted' with 'm' removed is 'prooted'.
'prooted' anagrammed gives 'TORPEDO'.
(Other definitions for torpedo that I've seen before include "To wreck" , "electric ray" , "Submarine weaponry" , "Poor Ted (anag)" , "Naval weapon" .)