Secure cheeky child the Spanish firework upset (11)
I believe the answer is:
impregnable
'secure' is the definition.
(I know that secure can be written as impregnable)
'cheeky child the spanish firework upset' is the wordplay.
'cheeky child' becomes 'imp' (imp is a kind of child. I am not sure about the 'cheeky' bit.).
'the spanish' becomes 'el' ('the' in Spanish).
'firework' becomes 'banger' (banger is a kind of firework).
'upset' says the letters should be written backwards.
'el'+'banger'='elbanger'
'elbanger' backwards is 'regnable'.
'imp'+'regnable'='IMPREGNABLE'
Can you help me to learn more?
(Other definitions for impregnable that I've seen before include "Unassailable" , "Not able to be overcome" , "Unable to be overcome" , "beyond doubt" , "Unable to be broken into" .)