Is it at the bottom of the make-up bag? (10)
I believe the answer is:
foundation
'make-up bag?' is the definition.
'foundation' can be an answer for 'make-up' (makeup for the face to give even complexion). I'm not sure about the 'bag?' bit.
'is it at the bottom of' is the wordplay.
I cannot really see how this works, but
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is located in the answer.
'at' could be 'on' (location) and 'on' is present in the answer.
'of' could be 'o' and 'o' is found in the answer.
This explanation may well be incorrect...
'the' acts as a link.
Can you help me to learn more?
(Other definitions for foundation that I've seen before include "cosmetic aid?" , "Base" , "Underlying basis" , "charity, say" , "Groundwork, basis" .)