Speedy firm? (4)
I believe the answer is:
fast
I believe this is a double definition.
'speedy' is the first definition.
('fast' can be similar in meaning to 'speedy')
'firm?' is the second definition.
('fast' can be a synonym of 'firm')
(Other definitions for fast that I've seen before include "Speedily - secured" , "Quick - abstain from food" , "Lent, perhaps" , "Dissolute" , "fare-dodging" .)