Convoy threat moving about (1-4)
I believe the answer is:
u-boat
'convoy threat' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'moving about' is the wordplay.
'moving' is an anagram indicator.
'about' is an anagram of 'U-BOAT'.
Can you help me to learn more?
(Other definitions for u-boat that I've seen before include "About (anag)" , "Submersible warship armed with torpedoes" , "German submarine of WW2" , "German World War One or World War Two submarine" , "Take pool exercise" .)