One of two giants crushing head of reckless spirit? (4)

I haven't cracked this one yet — but the brilliant team at Times for the Times have:

GOG (one of two giants) containing [crushing] R{eckless} [head of…]. I associate this with sea-farin’ folk. SOED advises it’s an abbreviation of ‘grogram’, originally a nickname of Admiral Vernon (1684–1757), who wore a grogram cloak, but afterwards applied to the mixture he ordered to be served out to sailors instead of neat rum.  Gog and Magog are two giants named in The Bible.