Pour tea to start: I must have mine to drink! (3,2,4)

'pour tea' is the definition.
'tip it down' can be an answer for 'pour' (both can mean to rain heavily). I'm unsure of the 'tea' bit.

'to start i must have mine to drink' is the wordplay.
'start' means to remove the last letter (I've seen 'starts' mean this).
'must have' says to put letters next to each other.
'mine' becomes 'pit' (down the pit).
'to drink' becomes 'down' (to down something can mean to drink it quickly).
'to' with its final letter removed is 't'.
't'+'i'+'pit'+'down'='TIP IT DOWN'