Grace perhaps, through catching some light (6)
I believe the answer is:
prayer
'grace perhaps' is the definition.
(grace is a kind of prayer)
'through catching some light' is the wordplay.
'through' becomes 'per' ('per' can mean through or by means of).
'catching' indicates putting letters inside.
'some light' becomes 'ray' (ray is a kind of light).
'per' placed around 'ray' is 'PRAYER'.
(Other definitions for prayer that I've seen before include "Paternoster, for example" , "Earnest hope" , "Words to a deity" , "Supplication ot God" , "Maybe collect" .)