Starting neutralising soil, in Guinea first, had a narrow escape (4,5)
I believe the answer is:
near thing
'a narrow escape' is the definition.
(something which nearly went badly)
'starting neutralising soil in guinea first' is the wordplay.
'starting' indicates taking the first letters.
'soil' becomes 'earth' (I've seen this before).
'guinea first' becomes 'g' (est letter of 'guinea').
The first letter of 'neutralising' is 'n'.
'n'+'earth'+'in'+'g'='NEAR THING'
'had' is the link.
(Other definitions for near thing that I've seen before include "almost an accident" , "dangerous" , "Even the short-sighted could plainly see that" , "Narrow escape, close shave" , "Narrow escape, missed by a small margin (4.5)" .)