Which 'Samasa' (compound structure) is present in the word 'देशप्रेम'?

Let's dissolve the compound word 'देशप्रेम' (Samasa Vigraha):
$$\text{देशप्रेम}=\text{देश के लिए प्रेम (Love for the country)}$$

Since a case-marker postposition ('के लिए', which is the case ending sign of Sampradan Karaka) is omitted during the combination of words, it falls under Tatpurusha Samasa (specifically Sampradan Tatpurusha).