Increased a good share of the reward (4)

I believe the answer is:

grew

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'increased' is the definition.
(growing is a kind of increasing)

'a good share of the reward' is the wordplay.
'a good' becomes 'g' (abbreviation).
'share of the reward' becomes 'rew' (I can't explain this - if you can you should believe this answer much more).
'g'+'rew'='GREW'

Can you help me to learn more?

(Other definitions for grew that I've seen before include "Expanded - flourished" , "Sprouted" , "Got bigger" , "Cultivated'" , "Multiplied" .)

I've seen this clue in the Evening Standard.

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