Longing to push teacher into the river (6)
I believe the answer is:
desire
'longing' is the definition.
(I've seen this in another clue)
'teacher into the river' is the wordplay.
'teacher' becomes 'sir' (way of addressing a male teacher).
'into' means one lot of letters goes inside another.
'the river' becomes 'Dee' (River Dee).
'sir' put within 'dee' is 'DESIRE'.
'to push' is the link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for desire that I've seen before include "Longing or wish" , "Reside (anag.)" , "Strong need" , "Hanker after" , "request" .)