Show up with former model (6)
I believe the answer is:
Here is my best explanation:
'show up' is the definition.
(I've seen this before)
'with former model' is the subsidiary indication.
'with' says to put letters next to each other.
'former' becomes 'ex'.
'model' becomes 'pose' ('pose' can be a synonym of 'model').
'ex' put next to 'pose' is 'expose'.
(Other definitions for expose that I've seen before include "Make visible or apparent", "Open to view", "Bring to light", "Bring into view", "Lay bare", "Lay open, reveal", "Uncover or unmask", "Uncover, expose to view", "Revelation of something discreditable - remove cover" and "Show up".)