Instruct male in type of wrestling close to Greco-Roman (6)

I believe the answer is:

summon

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'instruct' is the definition.
(both can mean to give orders)

'male in type of wrestling close to greco-roman' is the wordplay.
'male' becomes 'm' (common abbreviation).
'in' is an insertion indicator.
'type of wrestling' becomes 'sum' (I can't justify this - if you can you should believe this answer much more).
'close to' says to take the final letters (the close/ending of).
The final letters of 'greco roman' are 'on'.
'm' going inside 'sum' is 'summ'.
'summ'+'on'='SUMMON'

Can you help me to learn more?

(Other definitions for summon that I've seen before include "Convene" , "Call (someone) to a meeting" , "Request appearance of" , "Call (someone) to attend" , "Call (a person) to attend" .)

I've seen this clue in The Telegraph.

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