Fail to bring fake tan, initially (6)
I believe the answer is:
forget
'fail to bring' is the definition.
'fake tan initially' is the wordplay.
'fake' becomes 'forge' ('forge' can be a synonym of 'fake').
'initially' suggests taking the first letters.
The first letter of 'tan' is 't'.
'forge'+'t'='FORGET'
(Other definitions for forget that I've seen before include "Neglect (to do)" , "Slip one's mind" , "Be unable to remember" , "Stop remembering" , "Overlook" .)