In favour of exercises prior to run? Correct (6)
I believe the answer is:
proper
'correct' is the definition.
('proper' is associated in meaning with 'correct')
'in favour of exercises prior to run?' is the wordplay.
'in favour of' becomes 'pro' (I've seen this before).
'exercises' becomes 'pe'.
'prior to' says to put letters next to each other.
'run?' becomes 'r' (cricket abbreviation).
'pro'+'pe'+'r'='PROPER'
(Other definitions for proper that I've seen before include "Authentic" , "Genuine; suitable" , "Correct; formal" , "Appropriate description" , "Conforming to etiquette" .)