Significant road blunders - opening put off - opportunities for reflection? (7)
I believe the answer is:
mirrors
'opportunities for reflection?' is the definition.
'significant road blunders opening put off' is the wordplay.
'significant road' becomes 'mi' (resembles M1).
'blunders' becomes 'errors' (I've seen this before).
'opening put off' means to remove the first letter.
'errors' with its initial letter removed is 'rrors'.
'mi'+'rrors'='MIRRORS'
(Other definitions for mirrors that I've seen before include "Reflections" , "Reflects" , "Reflective pieces of glass" , "Shows a reflection" .)