Able to feel bliss, even not very upset (8)
I believe the answer is:
sensible
'able to feel' is the definition.
(sensible could once mean able to sense or feel )
'bliss even not very upset' is the wordplay.
'not' suggests deleting specific letters.
'very' becomes 'v' (abbreviation).
'upset' indicates an anagram.
'bliss'+'even'='blisseven'
'blisseven' with 'v' taken out is 'blisseen'.
'blisseen' with letters rearranged gives 'SENSIBLE'.
(Other definitions for sensible that I've seen before include "Practical, showing sound thinking" , "Showing good judgment" , "'Reasonable, judicious (8)'" , "Showing reason and sound judgment" , "Wise, prudent" .)