Note gun covering Tyler's power unit (8)
I believe the answer is:
megawatt
'power unit' is the definition.
(I know that megawatt is a type of power unit)
'note gun covering tyler's' is the wordplay.
I cannot really see how this works, but
'note' could be 'me' (alternative spelling the musical note mi) and 'me' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for megawatt that I've seen before include "Unit of electrical power" , "measure of power" .)