Hear sound of truck? (4-2)
I believe the answer is:
pick-up
This might be a double definition.
'hear sound' is the first definition.
'pick up' can be an answer for 'hear' (synonyms). I'm unsure of the 'sound' bit.
'truck?' is the second definition.
(pick-up is a kind of truck)
'of' is the link.
Can you help me to learn more?
(Other definitions for pick-up that I've seen before include "Improve, increase" , "Recover" , "Acquire by chance" , "Light open lorry with low sides and a tailboard" , "Small van" .)