Towards the centre, fold up (8)
I believe the answer is:
increase
'up' is the definition.
(I've seen this before)
'towards the centre fold' is the wordplay.
'towards the centre' becomes 'in' (as in moving in or closing in).
'fold' becomes 'crease' (creasing is a kind of folding).
'in'+'crease'='INCREASE'
(Other definitions for increase that I've seen before include "Grow greater" , "Amplification" , "Increment" , "extra money at work" , "Breed - nicer sea (anag)" .)