Pattern set in mechanical routine (7)
I believe the answer is:
rosette
'pattern' is the definition.
(I've seen this before)
'set in mechanical routine' is the wordplay.
'in' is an insertion indicator.
'mechanical routine' becomes 'rote' (I've seen this before).
'set' inserted inside 'rote' is 'ROSETTE'.
(Other definitions for rosette that I've seen before include "collection of ribbons" , "sign of a champion?" , "To steer (anag)" , "Ribbon badge for prize-winner" , "Prize; favour" .)