I examine the coloured cover, firmly fastened on (7)
I believe the answer is:
riveted
'fastened on' is the definition.
'riveted' can be an answer for 'fastened' (riveting is a kind of fastening). I am not certain of the 'on' bit.
'i examine the coloured cover firmly' is the wordplay.
I cannot quite understand how this works, but
'i' is found in the answer.
'examine' could be 'vet' (I've seen this before) and 'vet' is found within the answer.
'coloured' could be 'red' (similar in meaning) and 'red' is found within the leftover letters.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for riveted that I've seen before include "Rooted to the spot with metal pins" , "Fixed (as attention may be)" , "Made immovable - with steel pins?" , "Immovably fixed" , "Rendered motionless by concentration" .)