Person who eyes up first of girls in unusual role (5)
I believe the answer is:
ogler
'person who eyes up' is the definition.
'ogler' can be an answer for 'person' (ogler is a kind of person). I'm not sure about the rest of the definition.
'first of girls in unusual role' is the wordplay.
'first of girls' becomes 'g' (1st letter of 'girls').
'in' is an insertion indicator.
'unusual' indicates anagramming the letters.
'role' with letters rearranged gives 'oler'.
'g' going into 'oler' is 'OGLER'.
Can you help me to learn more?
(Other definitions for ogler that I've seen before include "Sexy looker" , "One staring" , "One who leers" , "one having inappropriate look?" .)