Puff guy's groovy ability up (10)
I believe the answer is:
airmanship
'puff guy's groovy ability up' is the definition.
I can't judge whether this defines the answer.
'puff guy's groovy ability up' is the wordplay.
'puff' becomes 'air'.
'guy' becomes 'man' (guy can informally mean a man).
'groovy ability' becomes 'pihs' (I can't explain this - if you can you should give a lot more credence to this answer).
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'pihs' in reverse letter order is 'ship'.
'air'+'man'+'ship'='AIRMANSHIP'
Can you help me to learn more?
(Another definition for airmanship that I've seen is " Need for pilot".)