Drool when rising tardily about four (8)
I believe the answer is:
salivate
'drool' is the definition.
(I know that drool is a more specific form of salivate)
'when rising tardily about four' is the wordplay.
'when' becomes 'as' (eg 'when I walked' means 'as I walked').
'rising' is a reversal indicator (going up in a down clue).
'tardily' becomes 'late' (synonyms).
'about' is an insertion indicator.
'four' becomes 'IV' (Roman numerals).
'as' in reverse letter order is 'sa'.
'late' placed around 'iv' is 'livate'.
'sa'+'livate'='SALIVATE'
(Other definitions for salivate that I've seen before include "Drool" , "Water at the mouth" , "Make mouth moisture in aestival manner" , "Produce moisture in mouth" , "Lisa a vet (anag.)" .)