Laid up with a bad face! (4)
I believe the answer is:
dial
'bad face' is the definition.
'dial' can be an answer for 'face' (face of a clock). I am unsure of the 'bad' bit.
'laid up' is the wordplay.
'up' is a reversal indicator (in down clue: letters go upwards).
'laid' in reverse letter order is 'DIAL'.
'with a' acts as a link.
Can you help me to learn more?
(Other definitions for dial that I've seen before include "Ring the clock-face" , "Calibrated disc etc" , "Face of a timepiece" , "Watch face" , "Meter face" .)