Ultimately storm surge bent ‘indestructible’ weather gauge (5)
I believe the answer is:
meter
'gauge' is the definition.
(I've seen this before)
'ultimately storm surge bent indestructible weather' is the wordplay.
'ultimately' suggests the final letters.
The final letters of 'storm surge bent indestructible weather' are 'METER'.
(Other definitions for meter that I've seen before include "Instrument for measuring quantity" , "Apparatus for measuring" , "Measuring device, say for electricity usage" , "Something measuring" , "Device to measure quantity used of fluid, electricity etc" .)