Easily impressed, possibly, by inside track (4)
I believe the answer is:
waxy
'easily impressed possibly' is the definition.
(wax can be pressed or impressed easily)
'by inside track' is the wordplay.
'by' becomes 'x' (multiplication sign).
'inside' means one lot of letters goes inside another.
'track' becomes 'way' (both can mean a path).
'x' inserted within 'way' is 'WAXY'.
(Other definitions for waxy that I've seen before include "Soft, pasty" , "Covered with a sticky substance" , "Irate; like candle" , "Irate; like a salad potato" , "Pallid, pasty; ceraceous" .)