Figure spread manure by lake (7)
I believe the answer is:
numeral
'figure' is the definition.
(I've seen this before)
'spread manure by lake' is the wordplay.
'spread' is an anagram indicator.
'by' means one lot of letters go next to another.
'lake' becomes 'L' (geographical abbreviation).
'manure' is an anagram of 'numera'.
'numera'+'l'='NUMERAL'
(Other definitions for numeral that I've seen before include "Figure representing an integer" , "one involved in maths?" , "1, 2, 3, say" , "Counting symbol" , "Symbol used to express quantity" .)