Unerringly squashes bug that's buzzing around tower (7)
I believe the answer is:
tugboat
'tower' is the definition.
(something which tows)
'unerringly squashes bug that's buzzing around' is the wordplay.
I cannot really understand how this works, but
an anagram of 'bug' is 'ugb' which is present in the answer.
'around' could be 'o' (I've seen this in other clues) and 'o' is present in the answer.
The remaining letters 'tat' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for tugboat that I've seen before include "Small vessel pulling a big one" , "Vessel drawing" , "Vessel towing larger vessels" , "Harbour craft" , "Powerful vessel used to pull larger ones" .)