Feel, to a minor degree, silly (9)
I believe the answer is:
senseless
'degree silly' is the definition.
'senseless' can be an answer for 'silly' (I've seen this before). I am not certain of the 'degree' bit.
'feel to a minor' is the wordplay.
'feel' becomes 'sense' (synonyms).
'to a minor' becomes 'less' (I've seen this before).
'sense'+'less'='SENSELESS'
Can you help me to learn more?
(Other definitions for senseless that I've seen before include "Inane" , "Not marked by the use of reason" , "Unconscious; stupid" , "Foolish; unconscious" , "Without reason" .)