Pretty tight, though in good running order (4-5)
I believe the answer is:
well-oiled
'running order' is the definition.
The definition suggests an adjective which matches the answer.
'pretty tight though in good' is the wordplay.
I cannot really understand how this works, but
'tight' could be 'oiled' (I've seen this in another clue) and 'oiled' is found in the answer.
'good' could be 'well' (similar in meaning) and 'well' is found within the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for well-oiled that I've seen before include "Drunk (as a smoothly working hinge?)" , "Thoroughly lubricated, or quite drunk" , "Drunk - without squeaks?" .)