Emma, Ben and Kelvin rebuilt National Trust mound (10)
I believe the answer is:
embankment
'mound' is the definition.
(I know that embankment is a type of mound)
'emma ben and kelvin rebuilt national trust' is the wordplay.
'and' is a charade indicator (letters next to each other).
'kelvin' becomes 'K' (abbreviation for the unit of temperature).
'rebuilt' indicates anagramming the letters.
'national trust' becomes 'nt'.
'emma'+'ben'+'k'='emmabenk'
'emmabenk' is an anagram of 'embankme'.
'embankme'+'nt'='EMBANKMENT'
(Other definitions for embankment that I've seen before include "Riverside wall" , "rampart" , "Needle here" , "Mound" , "protection against rising liquidity" .)