Unlikely to make the first move (3)
'unlikely to make the first move' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for shy that I've seen before include "Nervous or timid in company" , "Retiring; fling" , "Quick throw" , "'Timid, diffident (3)'" , "Recoil" .)
(Other definitions for timid that I've seen before include "Fearful - shy" , "not forward" , "Nervous and easily alarmed" , "Inclined to avoid people" , "Shrinking" .)