Face being laid up (4)
I believe the answer is:
dial
'face' is the definition.
(face of a clock)
'laid up' is the wordplay.
'up' says the letters should be written in reverse (in down clue: letters go upwards).
'laid' back-to-front is 'DIAL'.
'being' acts as a link.
(Other definitions for dial that I've seen before include "Calibrated disc etc" , "Ring the clock-face" , "Select a telephone number" , "Face of a timepiece" , "Watch face" .)