Plucking instrument, sentimental Zeus lost glimpse of Ulysses crossing river (8)
I believe the answer is:
tweezers
'plucking instrument' is the definition.
(tweezers are used to pluck things)
'sentimental zeus lost glimpse of ulysses crossing river' is the wordplay.
I cannot really understand how this works, but
'sentimental' could be 'twee' (I've seen this before) and 'twee' is found in the answer.
'river' could be 'r' (abbreviation for river) and 'r' is located in the answer.
This explanation may well be incorrect...
(Other definitions for tweezers that I've seen before include "Small hand tool used for gripping" , "Tool for extracting hairs" , "Hair pluckers" , "Implement for gripping small objects" , "Hair-pluckers" .)