Go-between introducing groom initially to wife-to-be (6)
I believe the answer is:
bridge
'go-between' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'introducing groom initially to wife-to-be' is the wordplay.
'introducing' means to remove the last letter.
'groom' becomes 'gel' (gelling is a kind of grooming).
'initially' is a charade indicator (letters next to each other).
'to wife-to-be' becomes 'brid' (I can't explain this - if you can you should give a lot more credence to this answer).
'gel' with its last letter taken away is 'ge'.
'ge' after 'brid' is 'BRIDGE'.
Can you help me to learn more?
(Other definitions for bridge that I've seen before include "Crossing structure" , "Requirement for spectacles" , "Card game - pontoon - couple" , "Card-game" , "Card game for four players" .)