Quiet leg-over will engross one (5)
I believe the answer is:
piano
'quiet' is the definition.
(I've seen this before)
'leg-over will engross one' is the wordplay.
I cannot quite understand how this works, but
'over' could be 'o' (cricket abbreviation) and 'o' is found in the answer.
'one' could be 'an' ('a' and 'an' can mean 'one') and 'an' is present in the answer.
The remaining letters 'pi' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for piano that I've seen before include "In music, soflty" , "Musical instrument - softly, please" , "Clavier" , "soft passage" , "Musical instrument - play quietly" .)