Floor covering log base in mullion moulding (8)
I believe the answer is:
linoleum
'floor covering' is the definition.
(I've seen this before)
'base in mullion moulding' is the wordplay.
'base' becomes 'e' (Euler's number - base of natural logarithms).
'in' is an insertion indicator.
'moulding' indicates an anagram.
'mullion' is an anagram of 'linolum'.
'e' placed within 'linolum' is 'LINOLEUM'.
'log' is the link.
I am not very happy about this link. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for linoleum that I've seen before include "Kind of floor covering with shiny surface" , "Stiff floor covering" , "Common floor covering, often in kitchen" , "Type of floor covering" , "Impregnated fabric for the floor" .)