Top geezer is match official (4,3)
I believe the answer is:
best man
'match official' is the definition.
The answer and definition can be both people as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'top geezer' is the wordplay.
'top' becomes 'best' (similar in meaning).
'geezer' becomes 'man' (I've seen this before).
'best'+'man'='BEST MAN'
'is' is the link.
Can you help me to learn more?
(Other definitions for best man that I've seen before include "Bridegroom's mate" , "Supporting male actor at a wedding" , "Groom's friend" , "Bridegroom's friend" , "Key union facilitator r" .)