Change size of study that’s risky, losing repeated item, after one takes the lead (7)

'change size of' is the definition.
(to make icon-sized)

'study that's risky losing repeated item after one takes the lead' is the wordplay.
I cannot really see how this works, but
'study' could be 'con' (conning is a kind of studying) and 'con' is found within the answer.
'one' could be 'i' (Roman numeral) and 'i' is found in the answer.
This explanation may well be incorrect...