General truth of maxim uncovered initially over minutes (5)
I believe the answer is:
axiom
'general truth' is the definition.
(I've seen this in another clue)
'maxim uncovered initially over minutes' is the wordplay.
'uncovered' says to take the centre.
'initially' says to take the initial letters.
The centre of 'maxim' is 'axi'.
The initial letters of 'over minutes' is 'om'.
'axi'+'om'='AXIOM'
'of' acts as a link.
(Other definitions for axiom that I've seen before include "Self-evident principle" , "Maxim - truism" , "Generally accepted truism" , "Universal principle" , "that goes without saying" .)