Order tabbouleh twice - in retrospect, somewhat steep (5)
I believe the answer is:
bathe
'steep' is the definition.
(I've seen this before)
'order tabbouleh twice in retrospect somewhat' is the wordplay.
'tabbouleh twice' can mean two replacements for 'tabbouleh'.
'somewhat' indicates the answer is hidden within the clue.
'in retrospect' is a reversal indicator.
'ehtab' is hidden within 'order tabbouleh tabbouleh'.
'ehtab' back-to-front is 'BATHE'.
(Other definitions for bathe that I've seen before include "Immerse in liquid for wash" , "Immerse oneself in water" , "Swim or paddle" , "Take a swim; envelop" , "plunge" .)